We plan to contine work in the structure and properties of the different forms of acetylcholinesterase. We will examine whether the subunits of the 11S form are identical and whether the other forms contain noncatalytic subunits. We will also explore the nature and function of secondary binding sites in acetylcholinesterase. BIBLIOGRAPHIC REFERENCE: "Free energy relationships in the inhibition of acetylcholinesterase by diethyl phosphates," Maglothin, J.S., Chen, W.-S. and Wilson, I.B., Mol. Pharmacol. 12, 658-666 (1976).